A lot of research and development activity has occurred for optical disk data recording wherein a laser system supplies a collimated light beam which is employed for recording data and for reading data recorded from a rotating optical record disk. An expensive portion of such data recorders is in the optical light path which includes optical wedges, beam splitters, a focus detector and a data modulator and detector. It is therefore advantageous to have a simplified and facile manufacturing method of assembling such wedges and beam splitters into such optical systems. In particular, it is desirable to make as many adjustments as possible independent of any other adjustments during fabrication or maintenance.
Another aspect, particularly for optical data recorders, concerns the shape of the recording and read back light beam. Generally a collimated diode or semiconductive laser beam from a semiconductive or diode laser has an elliptical shape. Such a shape is not conducive to maximizing data storage densities on an optical disk; a circular beam is desired. Accordingly, it is another object of the invention to provide a simplified beam-shape converter which is provided in conjunction with the aforementioned object.
Optical wedges have been employed in various types of optical devices for many years. For example, Linder U.S. Pat. No. 3,884,548, shows an optical wedge which transmits light to a mirror which in turn reflects the light at a given angle for stabilizing the optical system. According to the Linder patent, the optical wedge consists of an convex lens movably disposed in a concave cavity such that the two parts can be adjusted for changing the angle of the surfaces of the wedge. The light is transmitted first through the member having the concave cavity and then through the convex lens to the mirror.
Merkel, U.S. Pat. No. 3,253,525, shows another optical wedge which does not change the shape of the beam. The wedge itself is constructed similarly to the Linder illustrated wedge, but provides for relative movement between an image source and a convex lens while maintaining the spatial relationship between the concave member and the source, i.e. the concave member moves with respect to a fixed planar-convex lens; in other words, the planar surface of the planar convex lens is always maintained parallel to a given surface such that when any movement of the concave member there is a continuous correction of the image viewed at the focal point of the planar-concave lens. In other words, the shape of what is being viewed is maintained.
France Pat. No. 897,795 (published Mar. 30, 1945) shows a coin operated telescope with a variable optical wedge. The semicircular lens is rotated about a point which is the point of image input; this avoids any reflections from interfering with the viewing.